A study of soils is made in connection with the root studies, as the two are so closely related. After the study of roots and soils the other parts of the plant are considered in the order of their importance to the farmer or plant grower. The aim is always to get at fundamental facts and principles underlying all agricultural and horticultural practice. The author regards the conditions necessary to root growth and development as the important factor constituting soil fertility, and in the last ten chapters takes up the discussion of certain farm operations and practices and their effects on these necessary conditions, and consequently their effect on the fertility of the soil. The author extends gratitude to all who have in any way assisted in the preparation of this book, whether through advice, preparation of the text, preparation of the illustrations, or any other way in which he has received assistance. C.L. GOODRICH. GLENNDALE, Prince George Co., Maryland, _January_ 21, 1905. CONTENTS PART I GENERAL PRINCIPLES UNDERLYING PLANT CULTURE Chapter Page I.--INTRODUCTION TO PLANTS 3 II.--ROOTS 9 Uses of roots to plants 9 Habit of growth of roots 11 Conditions necessary for root growth 20 III.--SOILS 23 Relation of soil to plants 23 Classification of soils 26 How were soils made? 30 Soil texture 37 IV.--RELATION OF SOILS TO WATER 39 Importance of water to plants 39 Sources of soil water 40 Attitude of soils toward water: Percolation Absorption from below Power to hold water 40 The effect of working soils when wet 45 V.--FORMS OF SOIL WATER 48 Free water 48 Capillary water 49 Film water 50 VI.--LOSS OF SOIL WATER By surface wash By percolation and leaching By evaporation By transpiration How to check these losses 53